Chronic diseases contribute substantially to the morbidity of human populations and result in significant expenditures of public health dollars. Environmental agents may produce some of this disease, and identification of associations between exposures and certain diseases would presumably lead to the prevention of morbidity. Other than cancer, few chronic diseases have received much attention in studies of environmental hazards. The program in environmental exposures and chronic disease addresses the role of environmental factors in the etiology of some less well studied chronic diseases. The program is developing methodologies appropriate to the epidemiologic study of chronic diseases which are often difficult to characterize or define precisely, and is adapting methodologies that have been used in studies of cancer for use in studies of nonmalignant diseases. Current emphasis is on identifying risk factors for chronic renal disease. There are more than 50,000 individuals in the U.S. on maintenance dialysis for end stage renal disease at a cost of more than $1.5 billion per year. Dialysis patients represent only a fraction of those with some form of renal dysfunction. A multi-center case-control study of risk factors for chronic renal failure is nearing completion, as is a case-control study of risk factors for biopsy diagnosed IgA nephropathy. Related studies involve the development of a renal disease classification scheme for use in etiologic studies, and the analysis of vital statistics and NIOSH Occupational Hazards Survey data to identify time trends, geographic patterns of renal disease and occupations with potentially increased renal disease risk. Projects in other areas include analysis of data from the Health and Nutrition Examination Survey to develop a new estimate of the number of persons who have been exposed to asbestos.